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143 lines
4.9 KiB
EmacsLisp
143 lines
4.9 KiB
EmacsLisp
;;; scroll-bar.el --- window system-independent scroll bar support.
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;;; Copyright (C) 1993 Free Software Foundation, Inc.
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;; Maintainer: FSF
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;; Keywords: hardware
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;;; This file is part of GNU Emacs.
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;;; GNU Emacs is free software; you can redistribute it and/or modify
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;;; it under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 2, or (at your option)
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;;; any later version.
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;;; GNU Emacs is distributed in the hope that it will be useful,
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;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Emacs; see the file COPYING. If not, write to
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;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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;;; Code:
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;;; Commentary:
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;; Window-system-independent bindings of mouse clicks on the scroll bar.
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;; Presently emulates the scroll-bar behavior of xterm.
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;;; Code:
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(require 'mouse)
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;;;; Utilities.
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(defun scroll-bar-scale (num-denom whole)
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"Given a pair (NUM . DENOM) and WHOLE, return (/ (* NUM WHOLE) DENOM).
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This is handy for scaling a position on a scroll bar into real units,
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like buffer positions. If SCROLL-BAR-POS is the (PORTION . WHOLE) pair
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from a scroll bar event, then (scroll-bar-scale SCROLL-BAR-POS
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\(buffer-size)) is the position in the current buffer corresponding to
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that scroll bar position."
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;; We multiply before we divide to maintain precision.
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;; We use floating point because the product of a large buffer size
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;; with a large scroll bar portion can easily overflow a lisp int.
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(truncate (/ (* (float (car num-denom)) whole) (cdr num-denom))))
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;;;; Helpful functions for enabling and disabling scroll bars.
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(defvar scroll-bar-mode nil)
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(defun scroll-bar-mode (flag)
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"Toggle display of vertical scroll bars on each frame.
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This command applies to all frames that exist and frames to be
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created in the future.
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With a numeric argument, if the argument is negative,
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turn off scroll bars; otherwise, turn on scroll bars."
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(interactive "P")
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(setq scroll-bar-mode (if (null flag) (not scroll-bar-mode)
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(or (not (numberp flag)) (>= flag 0))))
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(mapcar
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(function
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(lambda (param-name)
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(let ((parameter (assq param-name default-frame-alist)))
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(if (consp parameter)
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(setcdr parameter scroll-bar-mode)
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(setq default-frame-alist
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(cons (cons param-name scroll-bar-mode)
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default-frame-alist))))))
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'(vertical-scroll-bars horizontal-scroll-bars))
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(let ((frames (frame-list)))
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(while frames
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(modify-frame-parameters
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(car frames)
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(list (cons 'vertical-scroll-bars scroll-bar-mode)
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(cons 'horizontal-scroll-bars scroll-bar-mode)))
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(setq frames (cdr frames)))))
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;;;; Buffer navigation using the scroll bar.
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(defun scroll-bar-set-window-start (event)
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"Set the window start according to where the scroll bar is dragged.
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EVENT should be a scroll bar click or drag event."
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(interactive "e")
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(portion-whole (nth 2 end-position)))
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(save-excursion
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(set-buffer (window-buffer window))
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(save-excursion
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(goto-char (scroll-bar-scale portion-whole (buffer-size)))
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(beginning-of-line)
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(set-window-start window (point))))))
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(defun scroll-bar-scroll-down (event)
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"Scroll the window's top line down to the location of the scroll bar click.
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EVENT should be a scroll bar click."
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(interactive "e")
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(let ((old-selected-window (selected-window)))
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(unwind-protect
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(progn
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(portion-whole (nth 2 end-position)))
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(select-window window)
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(scroll-down
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(scroll-bar-scale portion-whole (1- (window-height))))))
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(select-window old-selected-window))))
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(defun scroll-bar-scroll-up (event)
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"Scroll the line next to the scroll bar click to the top of the window.
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EVENT should be a scroll bar click."
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(interactive "e")
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(let ((old-selected-window (selected-window)))
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(unwind-protect
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(progn
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(let* ((end-position (event-end event))
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(window (nth 0 end-position))
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(portion-whole (nth 2 end-position)))
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(select-window window)
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(scroll-up
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(scroll-bar-scale portion-whole (1- (window-height))))))
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(select-window old-selected-window))))
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;;;; Bindings.
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;;; For now, we'll set things up to work like xterm.
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(global-set-key [vertical-scroll-bar mouse-1] 'scroll-bar-scroll-up)
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(global-set-key [vertical-scroll-bar drag-mouse-1] 'scroll-bar-scroll-up)
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(global-set-key [vertical-scroll-bar mouse-2] 'scroll-bar-set-window-start)
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(global-set-key [vertical-scroll-bar drag-mouse-2] 'scroll-bar-set-window-start)
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(global-set-key [vertical-scroll-bar mouse-3] 'scroll-bar-scroll-down)
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(global-set-key [vertical-scroll-bar drag-mouse-3] 'scroll-bar-scroll-down)
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(provide 'scroll-bar)
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;;; scroll-bar.el ends here
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